Some factors behind density dynamics of bat flies (Diptera: Nycteribiidae) ectoparasites of the boreal chiropterans: omitted predictors and hurdle model identification

We investigated density dynamics of three bat flies species (Diptera, Nycteribiidae): Penicillidia monoceros Speiser, 1900, Nycteribia quasiocellata (Theodor, 1966), Basilia rybini (Hurka, 1969) parasitized on two host species: pond bat, Myotis dasycneme (Boie, 1825), and eastern water bat, Myotis petax Hollister, 1912. Females of M. dasycneme have 3.4 (95 % CI 1.4–8.3) times higher odds of being infested, and in 2.4 (1.5–3.7) times higher average number of P. monoceros than males. Similarly, females of M. petax have 1.7 (1.2–2.4) times higher density of N. quasiocellata and/or B. rybini. We hypothesized an existence of host-sex-recognition mechanism in bat flies, providing it fine “ecological profit” due to sex-biased dispersal among adult host during wintering and the chance to infested a host offspring later (in summer). The decrease (due to mortality or emigration) in density of bat flies can be described as simple harmonic or S-shaped curve, and its “step” apparently corresponds to time of host pairing